The exemplary embodiments of this invention relate generally to semiconductor devices and, more particularly, to metal gates for use with borderless self-aligning contacts in semiconductor devices.
In the manufacture of an integrated circuit (IC) chip, various semiconductor devices (such as field effect transistors) can be fabricated on a supporting substrate using various deposition techniques. Current flows within the semiconductor device from a source to a drain. A gate generates an electric field that controls the current flow.
Precise alignment of the semiconductor device to maintain contact with the source, drain, and gate is not always possible, particularly as the number of devices on an IC chip increases or as trends in semiconductor fabrication progress toward further size reduction. In either case, the use of “borderless” self-aligning contacts (SACs) is employed. In the technology of borderless SACs, the edges of a gate or gate conductor may overlap the source or drain and contact the semiconductor device without interfering with the operation of the semiconductor device.
Gates and gate conductors in semiconductor devices have typically been fabricated of polysilicon. In order to obtain faster speeds in semiconductors, polysilicon gates can be replaced with metal gates. However, current semiconductor manufacturing technology does not support suitable control in the operation of semiconductor devices employing these replacement metal gates (RMGs) in conjunction with borderless SACs.